1. Field of the Invention
The invention relates to check valves and more particularly to an improved trim of a check valve.
2. Description of Related Art
Valve is a device that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves have many uses, including controlling water for Irrigation, industrial uses for controlling processes, water and sewage processing, mining, power generation, processing of oil, gas and petroleum, food manufacturing, chemical and plastic manufacturing, military and transport sectors, and many other fields.
Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave. There are various types of check valves used in a wide variety of applications. Although they are available in a wide range of sizes and costs, check valves generally are very small, simple, and/or inexpensive. Check valves work automatically and most are not controlled by a person or any external control. However, many typically the check valves have the drawbacks of being stuck, compromised leak-tight seat, large sediment accumulation, etc.
China Utility Model No. 01276666.6 granted in 2002 discloses a check valve having a double trim as detailed below. A stem 3 is able to move in a guide sleeve 1. A double trim 5 is connected to a front portion. The double trim 5 has a sealing ring on each of a plurality of layers. A spring 4 is put on the double trim 5 so that a turning of the stem 3 can move further into an outlet for blocking a reverser flow in cooperation with a wedge shaped structure and the sealing rings. However, the guide sleeve 1 is relatively elongated so that a traveling distance of the stem 3 is long. Further, sediment accumulated on an inner surface of the guide sleeve 1 can hinder the movement of the stem 3. After a long period time of use, the stem 3 may be stuck in the guide sleeve 1 with the desired leak-proof function compromised. Furthermore, the elongated stem 3 may be bent due to long time collision with fluid flow. The bent stem 3 also may be easily stuck. In addition, the double trim 5 has it leak-proof function being implemented by tightly compressing the sealing rings onto the outlet. However, the sealing by the sealing rings may be compromised after a period time of use due to the nature of the plastic sealing rings or due to excessive high pressure of fluid flow. Additionally, the valve is relatively large due many parts such as the stem 3, the guide sleeve 1, a handle 10, etc. And in turn, it can limit its applications and adversely increase the manufacturing cost.
U.S. Pat. No. 8,402,991 to Wu discloses an outlet valve for a frost-preventing faucet employing an axial slot at a central top inside the inlet passage for being inserted by an spring and an axial post. A first stop ring is disposed around the stop valve. The first stop ring and the stop valve are inserted into a limiting slot of a stop sleeve under the stop valve. A second stop ring around the stop sleeve is inserted into a lower section of an inner wall of the inlet passage. A bottom of the second stop ring is disposed above the top porcelain. Cooperating the subject configuration with the top porcelain allows the water to be supplied upward since outlet gates of the bottom porcelain and the top porcelain stay abreast without blockage. When a water pressure is greater than a restoring force of the spring, the stop valve upwardly compresses the spring. Thereby, water flows through the inlet passage at a middle portion of the plug and enters into an outlet at a top end of the tubular valve seat. The water is further upwardly guided into a supplying pipe of the faucet. When the water pressure is less than the restoring force of the spring, the spring compresses the stop valve. Thereby, an axial post of the stop valve is downwardly inserted into the limiting slot of the stop sleeve to stop the water flow. Thus the porcelain valve unit is prevented from freezing, and the water pressure is capable of controlling the water flow.
Notwithstanding the prior art, the invention is neither taught nor rendered obvious thereby.